Serum albumin is present in blood plasma in a proportion higher than any other plasma protein and functions to maintain an osmotic pressure or to carry nutrients, metabolites, etc. as a combination therewith in blood.
Preparations containing serum albumin are used in the treatment of hypoalbuminemia, hemorrhagic shock, etc. caused by albumin depletion or reduction of albumin biosynthesis. To deactivate viruses which may be incorporated into the albumin preparations, a heat treatment of an albumin-containing aqueous solution is generally carried out. It is known that commercially available albumin preparations obtained from the thus treated albumin aqueous solution contain agglomerates (hereinafter referred to as polymers as such agglomerates are commonly called) which have been formed during preparation. From the fact that no substantial polymers are found before the above-described heat treatment, it is believed that heat-labile proteins are partially denatured by the heat treatment to form polymers. Considering that the commercially available albumin preparations have been widely used with safety, these polymers are not regarded particularly harmful to human bodies. However, it is desired that the preparations contain no polymers because the polymers are heat denaturation products.
Further, albumin preparations also contain .alpha..sub.1 -acid glycoprotein (hereinafter referred to as .alpha..sub.1 -AGP), having an immunosuppressive activity, as an impurity. .alpha..sub.1 -AGP is a protein somewhat similar to albumin in physicochemical properties and, therefore, it is difficult to efficiently separate .alpha..sub.1 -AGP from albumin by commonly employed means, such as fractionation. Hence, there is a fear that usual albumin preparations contain residual .alpha..sub.1 -AGP having an immunosuppressive activity, and it is desired to remove .alpha..sub.1 -AGP from the preparations to the extent possible.